Substrate processing apparatus and method

ABSTRACT

The invention relates to a substrate processing apparatus comprising a reaction chamber provided with a substrate rack for holding a plurality of substrates in the reaction chamber. The substrate rack may have a plurality of spaced apart substrate holding provisions configured to hold the plurality of substrates. The apparatus may have an illumination system constructed and arranged to irradiate radiation with a range from 100 to 500 nanometers onto a top surface of the substrates.

FIELD

The present invention generally relates to a substrate processing apparatus and method. More particularly, the invention relates to a substrate processing apparatus comprising a reaction chamber provided with a substrate rack for introducing a plurality of substrates in the reaction chamber, the substrate rack comprising a plurality of spaced apart substrate holding provisions configured to hold the plurality of substrates in a spaced apart relationship.

BACKGROUND

Furnaces, functioning as reactors, may be used as a reaction chamber to create fine dimension structures, such as integrated circuits, on a substrate. Several substrates, such as silicon wafers, may be placed on a substrate holder, such as a substrate rack or boat inside the reactor. In a typical substrate treatment step the substrates may be heated. Further, reactant gases may be passed over the heated substrate, causing the deposition of a thin layer of the reactant material or reactants of the gases on the substrate to be treated.

A series of treatment steps on a substrate is called a recipe. If the deposited layer has the same crystallographic structure as the underlying silicon substrate, it is called an epitaxial layer. This is also sometimes called a monocrystalline layer because it has only one crystal structure. Through subsequent deposition, doping, lithography, etch and other processes, these layers are made into integrated circuits, producing from tens to thousands or even millions of integrated devices, depending on the substrate size and the circuits' complexity.

Various process parameters are carefully controlled to ensure the high quality of the resulting layers. One such critical parameter is the substrate temperature during each recipe step. During CVD, for example, the deposition gases react within particular temperature windows and deposit on the substrate. Different temperatures result in different deposition rates and quality. Accordingly, it is important to accurately control the substrate temperature to bring the substrate to the desired temperature before the reaction treatment begins. The substrate may comprise features that are temperature sensitive and therefor the temperature may be limited to a certain maximum to avoid damage to those sensitive features.

For certain processes, energy may be necessary at the top surface of the. If this energy is provided in the form of heat this may lead to contradicting requirements in which for productivity, quality and/or reactivity, the temperature should be high, while to avoid damage to the features on the substrate the temperature should remain low.

SUMMARY

Accordingly, there may be a need for providing energy to a surface of a plurality of substrates in a reaction chamber.

In accordance with at least one embodiment of the invention there is provided a substrate processing apparatus comprising:

a reaction chamber; and

a substrate rack for providing a plurality of substrates in the reaction chamber. The substrate rack may comprise a plurality of spaced apart substrate holding provisions configured to hold the plurality of substrates in a spaced apart relationship. The apparatus may comprise an illumination system constructed and arranged to irradiate ultraviolet radiation within a range from 100 to 500 nanometers onto a top surface of at least one of the substrates in the substrate rack from a side of the substrate rack.

By irradiating the surface of the substrates from the side with ultraviolet radiation, it may be possible to provide energy on the top surface. The illumination system may be constructed and arranged to radiate ultraviolet radiation with a range from 100 to 500, preferably 150 to 400, and even more preferably 170 to 300 nanometers. The substrate rack may be moveable into the reaction chamber.

In accordance with a further embodiment of the invention there is provided a substrate processing method, comprising:

providing a plurality of substrates in a substrate rack comprising a plurality of spaced apart substrate holding provisions configured to hold the plurality of substrates in a spaced apart relationship; and,

irradiating ultraviolet radiation within a range from 100 to 500 nanometers to the substrates in the substrate rack in the reaction chamber from a side of the substrate rack.

For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE FIGURES

It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure.

FIG. 1 shows, diagrammatically and partially exposed, a perspective view of the apparatus for application of the illumination system according to an embodiment;

FIG. 2 shows, diagrammatically, a plan view of the apparatus according to FIG. 1;

FIG. 3 shows a cross-section of a substrate rack with a substrate that is illuminated with an illumination system according to an embodiment;

FIG. 4a shows an illumination system formed in a helical form according to an embodiment;

FIG. 4b depicts a portion of a gas discharge lamp for use in an illumination system according to an embodiment;

FIGS. 5a, 5b, and 5c depict an illumination system transmitting radiation according to an embodiment;

FIGS. 6a, 6b, and 6c depict an illumination system transmitting radiation according to a further embodiment;

FIGS. 7a and 7b depict an illumination system transmitting radiation according to yet a further embodiment;

FIGS. 8a, 8b, and 8c depict apparatus comprising an illumination system according to further embodiments;

FIG. 9 depicts an illumination system according to a further embodiment;

FIG. 10 depicts a substrate processing apparatus comprising an illumination system according to a further embodiment;

FIG. 11 depicts a problem that may arise in the apparatus using the illumination system according to FIG. 10; and,

FIG. 12 depicts a solution to the problem of FIG. 11.

DETAILED DESCRIPTION

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below.

An apparatus 1 for using the illumination system according to an embodiment may be indicated in FIGS. 1 and 2. Said apparatus 1 may comprise a housing 2 and may in general being installed partially or completely in a so-called “clean room”. In addition to housing 2, partitions 3, 4 and 5 may be present, as can be seen in particular from FIG. 2. Housing 2 may delimit, with partition 3, reactor area 21. A substrate handling chamber 22 may be delimited between housing 2 and partitions 3, 4. A cassette handling chamber 23 may be delimited between partitions 4 and 5 and housing 2. The apparatus 1 may further comprise a cassette introduction portion 33.

Two reactor chambers 6, 7, may be arranged in reactor area 21, however also a single reactor chamber may be used. Said reactor chambers may be positioned vertically and substrate racks, indicated by 12, filled with substrates 13, may be moved into the reactor chambers 6, 7 in the vertical direction from below. To this end each reactor chamber may have a rack handler comprising an insertion arm 14, which is movable in the vertical direction with the aid of a spindle 38. Only one insertion arm 14 can be seen in the drawing of FIG. 1; however there may be two insertion arms 14 on both sides of the apparatus.

The substrate rack 12 may be provided at the bottom with an insulating plug, which is not indicated in more detail, which provides a seal with respect to the reactor chamber. The reactor chamber may be referred to as a furnace and may be provided with a heater to heat the substrates.

The rack handler further may comprise a rotary platform 11, provided with cut-outs 15, arranged in the reaction area 21. Said cut-outs 15 may be shaped such that, if the cut-outs 15 have been brought into the correct position, arm 14 is able to move up and down through the cut-outs. On the other hand, the diameter of the bottom of the substrate rack may be such that said diameter is larger than the cut-out 15 in the platform 11, so that when the arm 14 moves downwards from the position shown in FIG. 1, the substrate rack 12 may be placed on rotary platform 11 and may be removed therefrom again in a reverse operation.

The substrate racks 12 may be fed to both reactor chambers 6 and 7 with the rack handler. It may be possible to perform a successive treatment therein. It may also be possible to allow parallel groups of substrate racks 12 to be treated exclusively by reactor chamber 6 and exclusively by reactor chamber 7. Said substrate racks 12 may be provided with substrates 13.

Substrates 13 may be supplied in (transport) cassettes 10 which, from the cassette introduction portion 33, may be placed in store 8 through a closable opening 34 with the aid of arm 31 of the cassette handling robot 35. Arm 31 may be provided with a bearing surface 32 which has dimensions a little smaller than those of the series of cut-outs 26 in rotary platforms 27. A number of such rotary platforms may be provided one above the other in the vertical direction in store 8. Arm 31 may be movable in the vertical direction with the aid of cassette handling robot 35. Arm 31 may be mounted such that said arm is able not only to pick up or remove cassettes from or to introduction portion 33 to or from store 8, but also to make it possible to move cassettes from or to store 8 to or from rotary platform 30.

Said rotary platform 30 may be constructed such that on rotation the cassette is placed against partition 4 where an opening 37 has been made so that, after opening the cassettes, substrates can be taken one by one from the cassette concerned with the aid of arm 24 of a substrate handler and can be placed in the substrate rack 12 located in substrate handling chamber 22. Said substrate rack 12 is supported by a hinged arm 16 being part of the rack handler and provided with a bearing surface 17 at the end, the dimensions of which are somewhat smaller than those of cut-outs 15 of rotary platform 11. Said arm 16 may be able to move with the substrate rack through a closable opening in partition 3 by rotation about rotation point 18. A closure may be provided in order to be able to close opening 19 between reaction area 21 and substrate handling chamber 22.

An operator or an automated cassette transport system (not shown), may load store 8 by introducing a number of cassettes on introduction portion 33. Control operations may be done on panel 36. Cassettes 10 may be transferred from the introduction portion 33 with the aid of arm 31 into the storage compartments 9 made for these cassettes in store 8. By starting from the lowest position for removing the relevant cassette 10 from portion 33 through the opening 34, said cassette can be moved upwards for moving into a higher compartment 9 of the store 8 by the cassette handling robot 35. By rotation of the store 8 it is possible to fill various compartments 9 with cassettes 10.

The cassettes 10 concerned may be removed from the store by arm 31 and placed on rotary platform 30. The cassettes are rotated on the rotary platform 30 and placed with their door against partition 4. The door of the cassette may be removed with a door opener. With the aid of arm 24, the substrates may be removed substrate by substrate and placed in substrate rack 12 placed on swing arm 16 with the substrate handler.

In the interim the rotary platform 11 may be able to move in the reactor area 21 in an optimum manner with regard to the treatments to be carried out on the substrates present inside the reactor area 21. After substrate rack 12 has been filled in the substrate handling chamber 22 and may become available to one of the reactor chambers 6, 7, opening 19, which was closed up to this time, is opened and said freshly filled substrate rack 12 may be placed on rotary platform 11. Said rotary platform 11 may then move one position and the filled substrate rack 12 may be removed from platform 11 with the help of insertion arm 14 into the reactor chambers 6, 7. Treated substrates in a finished rack may be lowered on said filled platform 11. Said substrates execute a movement counter to the above to end up in the cassettes.

The substrate rack 12 with the fresh substrate may be fed to reactor chamber 6 or 7 with the insertion arms 14 and may be treated in said chamber. It may be possible to perform a successive treatment in the reactor chamber 6, 7. As depicted the apparatus may have two reactor chambers 6, 7, but the apparatus may have also one reactor chamber or three or more reactor chambers without departing from the scope of invention.

The treatment may comprise an increase of the temperature of the substrates in the substrate rack 12 with a heater. It is important to accurately control the substrate temperature to bring the substrate to the desired temperature before the treatment begins to get the right productivity. Further the substrate may comprise features that are temperature sensitive and therefor the temperature may be limited to a certain maximum to avoid damage to those sensitive features. This may lead to contradicting requirements in which for reactivity the temperature of the substrate may be high while the temperature of the substrate may be low to avoid damaging the temperature sensitive features on the substrate.

The apparatus may comprise an illumination system constructed and arranged to irradiate ultraviolet radiation within a range from 100 to 500 nanometers onto a top surface of at least one of the substrates in the substrate rack from a side of the substrate rack. The illumination system may be constructed and arranged to radiate ultraviolet radiation with a range from 100 to 500, preferably 150 to 400, and even more preferably 170 to 300 nanometers. By irradiating the top surface of the substrates from the side with ultraviolet radiation it may be possible to provide energy to the top surface for certain processes.

The energy may increase the reactivity on the top surface. This increase of reactivity may be accomplished while not overheating the substrate so that temperature sensitive features on the substrate may not get damaged. The increase of reactivity may lead to a better quality of the deposited layer and/or a higher productivity of the apparatus. It may also lead to certain processes becoming possible at a temperature on which before they were not possible because the reactivity was zero.

FIG. 3 shows a cross-section of a substrate rack 12 with a substrate 13 that is illuminated from four sides. The illumination system 41 may therefore comprise four parts to irradiate ultraviolet radiation to the substrate 13 from multiple sides. The illumination system 41 may be configured to irradiate ultraviolet radiation within a range from 100 to 500 nanometers.

The parts of the illumination system 41 may be elongated and extend in a direction perpendicular to the substrate surface. The parts of the illumination system 41 may extend over a part of the rack 12, over the full length of the rack 12 or even a bit further. The parts of the illumination system may have a length of between 50 and 200 cm, preferably 75 and 150 cm to illuminate the substrates over the full length of the rack 12.

The illumination system 41 for illuminating the substrate surface may have a power of between 5 W and 100 kW, preferably 300 W and 20 kW and even more preferably between 1 and 10 kW. The illumination system may have an efficiency of between 50 and 90% in the conversion of electrical energy to ultraviolet radiation. The illumination system may have a power output of between 0.05 W and 1 kW per centimeter, preferably between 3 and 200 W per centimeter and most preferably between 10 and 100 W per centimeter in the direction perpendicular to the substrates. The substrate surface may receive a power between 0.1 and 200 milliwatt (mW)/cm², preferably between 1 and 100 mw/cm² and even more preferably between 5 and 80 mW/cm². The illumination system may be constructed and arranged to radiate ultraviolet radiation with a range from 100 to 500, preferably 150 to 400, and even more preferably 170 to 300 nanometers. The rack 12 may have a distance between 50 and 200 cm.

The substrate 13 may be positioned in the substrate rack 12 which may comprise three struts comprising a plurality of spaced apart substrate holding provisions configured to hold the plurality of substrates in a spaced apart relationship. The rack 12 may have a maximum of between 50 and 200, preferably between 100 and 180 spaced apart substrate holding provisions along the struts for holding an equal amount of substrates.

For an optimal production the rack may be filled until the maximum however to increase the power received on the substrates and to improve the uniformity of the radiation received over the surface of the substrate the number of substrates in the rack 12 may be made lower than the maximum. For example, the rack may be provided with 10 to 80 of substrates in a spaced apart relationship. The distance between the substrates in the rack may in such case between 5 to 200, preferably 20 to 140 and most preferable between 40 mm to 100 mm.

The struts may be elongated and extend in a direction perpendicular to the substrate surface. The plurality of substrates may be positioned parallel with each other in the substrate rack 12. The configuration of the substrate rack 12 and the illuminations system 41 causes the illumination 41 to irradiate the ultraviolet radiation onto a top surface of at least one of the substrates in the substrate rack from a side of the substrate rack 12. As depicted the illumination system may comprise four parts to irradiate ultraviolet radiation from four sides to the substrate. Illuminating from four sides may improve the uniformity of the illumination received on the substrate. The illumination system may also have one, two, three or four parts which illuminate the substrate surface.

Ultraviolet radiation may be creating a plasma in gasses through which it may traverse. The plasma may be helpful or unwanted for the processes that we are running in the reaction chamber. If the plasma is unwanted, the apparatus may be constructed and arranged to suppress plasma in the reaction chamber 6. The apparatus may also be constructed and arranged to obstruct the plasma from propagating into the reaction chamber 6. For example, by providing the apparatus with plasma shielding, e.g., conductive wiring or coatings the plasma may be suppressed or obstructed before it reaches the reaction chamber. The apparatus may also be provided with a program which when run on the apparatus selects the gas, pressure range and/or power range such that the creation of a plasma in the interior of the reaction chamber 6 may be suppressed.

FIG. 4a shows an illumination system 41 formed in a helical form which may be used to illuminate the top surface of the substrates. The helically formed illumination system may be configured surrounding a substrate rack 12 with substrates 13. The illumination system 41 may be a gas discharge lamp.

FIG. 4b depicts as a portion of a gas discharge lamp. Gas discharge lamps generate radiation by having an electric discharge between two electrodes through an ionized gas, e.g., a plasma in a tube 43. Such lamps may use a noble gas such as argon, neon, krypton, and xenon or a mixture thereof and additionally even may use mercury, sodium, and metal halides in the mixture in the tube 43. The electrons may be forced to leave atoms of the gas near an anode by the electric field applied between the two electrodes from which only one 45 is depicted, leaving these atoms positively ionized. Free electrons flow to the anode, while the cations flow to the cathode. The ions may collide with neutral gas atoms, which transfer their electrons to the ions. The atoms, having lost an electron during the collisions, ionize and speed toward the cathode while the ions, having gained an electron during the collisions, return to a lower energy state while releasing energy in the form of radiation which is emitted in the direction of the substrate top surface of the substrate to transfer its energy into the top surface. The electrode 45 is mounted in a base 47 connected to the tube 43 and being provided with pins 49 to provide power to the electrodes 45.

FIGS. 5a-5c depict an illumination system transmitting radiation according to an embodiment. In FIG. 5a , a top view on the illumination system 41 configured in a reaction chamber 6 is shown. In FIG. 5b , an enlarged top view on the illumination system 41 of FIG. 5 a is shown. The illumination system 41 is provided with a radiation transmitting surface 53 and a reflecting surface 55 to direct the ultraviolet radiation 51 towards the substrates. The radiation transmitting surface 53 may be part of the tube 43 of the discharge lamp of FIG. 4.

In between the radiation transmitting surface 53 and the reflecting surface 55 a gas 57 may be provided (see FIG. 5c which is side view on the illumination system 41 of FIG. 5a ). The apparatus may be provided with a purge system for purging the radiation transmitting or reflecting surfaces 53, 55 in the reaction chamber with a purge gas 57. The purge gas may create a gas flow through the illumination system 41 towards the opening through which the radiation 51 is transmitted. The purge system may be provided with a control system 54 for controlling a valve 56 for providing the purge gas in the reaction chamber 6 from the fluid storage 58 via the illumination system 41.

The gas flow may counteract any contamination or deposition on the radiation transmitting or reflecting surfaces 53, 55 caused by gases from the reaction chamber 6. Such contamination or deposition may deteriorate the transmission of radiation by the radiation transmitting surface 53 or the reflection by the reflecting surface 55. In this way the illumination system 41 comprising the radiation transmitting and/or reflecting surface may be provided partially within the reaction chamber.

The apparatus may be provided with at least one injector. The injector may be provided within the reaction chamber for providing a fluid into the reaction chamber. A purge or processing gas may be provided through the injector. As an option the illumination system 41 may be constructed and arranged in an injector to provide the radiation and or the purge or processing gas through the injector to the substrates. This may be done in a similar way as depicted in FIGS. 5a to 5 c.

The processing gas may be selected such that it is reactive when applied within the reaction chamber 6 but not reactive when in the injector because otherwise it may deteriorate the transmission of radiation by the radiation transmitting surface 53 or the reflection by the reflecting surface 41. For example, the processing gas may be a first precursor reactive with another second precursor but not reactive in absence of the other precursor.

The apparatus provided with the illumination system may be provided with a fluid system comprising a control system 54 for controlling a valve 56 for providing the fluid such as a processing or purge gas in the reaction chamber. The fluid may be stored in the fluid storage 58 or may be received from a gas line. The control system and the valve 56 may be constructed and arranged to perform an atomic layer deposition (ALD) or chemical vapor deposition (CVD) cycle on the substrate with a first and/or second precursor stored in a fluid storage 58.

FIGS. 6a-6c depict an illumination system transmitting radiation according to a further embodiment. In FIG. 6a , a top view on the illumination system 41 configured in a reaction chamber 6 is shown. In FIGS. 6b and 6c , an enlarged side view on the illumination system 41 of FIG. 6a is shown. The illumination system 41 is provided with a radiation transmitting surface 53 to direct the ultraviolet radiation towards the substrates. The radiation transmitting surface 53 may be part of the tube 43 of the discharge lamp of FIG. 4.

The radiation transmitting surface 53 may be provided with a fluid 57. The fluid 57 may be a purge gas or a processing gas. The apparatus may be provided with a purge system for purging the radiation transmitting surface 53 with the gas flow of a purge or processing gas in the reaction chamber 6. The gas flow whether it is a purge gas or a processing gas may counteract any contamination or deposition on the radiation transmitting surface caused by gases from the reaction chamber 6. Such contamination or deposition may deteriorate the transmission of radiation by the radiation transmitting surface 53. In this way the illumination system 41 comprising the radiation transmitting surface 53 may be provided partially within the reaction chamber 6.

The apparatus provided with the illumination system may be provided with a fluid system. The fluid system may comprise a fluid control system 54 for controlling a valve 56 for providing the fluid such as a processing or purge gas in the reaction chamber 6. The fluid may be stored in a fluid storage 58 or may be from a gas line.

The ultraviolet radiation can be used to deposit, densify, atomic layer (ALD), chemical vapor deposition (CVD) or other layers. When layers of, for example, silicon or silicon nitride are deposited in a reaction chamber the efficiency of the ultraviolet radiation system may be reduced by absorption when a thickness of deposited material is adding up on top of the radiation transmitting surface. Purging the radiation transmitting surfaces may be alleviating this issue to some extent.

A complementary periodical in situ clean with etch gases may be a required to clean the radiation transmitting or reflecting surface 53. The apparatus may comprise an etching system. The etching system may comprise a fluid storage 58, a control system 54 and a valve 56. The control system 54 may be provided with a program when run on the control system to improve the transmissivity of the radiation transmitting or reflecting surface after a layer is deposited on the radiation transmitting or reflecting surface.

An etching fluid may be stored in the fluid storage 58 of the etching system. The control system 54 may be controlling a valve 56 for providing the etching fluid in the reaction chamber 6. The control system may controls the valve 56 to provide the etching fluent, i.e., etchant in the reaction chamber so as to etch a layer deposited on the radiation transmitting 53 or reflecting surface away to improve the transmissivity of the surface.

The etching fluid may be chloride (Cl₂), boriumchloride (BCl₃), hydrogenchloride (HCl), tetrafluoromethane (CF₄), nitrogentrifluoride (NF₃), hydrogenbromide (HBr), sulfur hexafluoride (SF₆), or an ashing component created by ultraviolet radiation in combination with an hydrogen or oxygen comprising gas such as hydrogen or oxygen. The periodical in situ clean with etch gases may also be used as an alternative for purging the radiation transmitting or reflecting surfaces which may simplify the design of the apparatus.

The radiation transmitting surface 53 or reflecting surface 55 may also be made transmissive or reflective for the illumination radiation again by periodically converting the silicon or silicon nitride layers into silicon oxide by a thermal treatment in an oxidizing environment. The apparatus may comprise a conversion system. The conversion system may comprise the fluid storage 58, the control system 54 and the valve 56. The control system 54 may be provided with a program when run on the control system to improve the transmissivity of the radiation transmitting or reflecting surface after a layer is deposited on the radiation transmitting or reflecting surface.

An oxygen comprising fluid such as, for example, oxygen (O₂), ozone (O₃), peroxide (H₂O₂), water (H₂O), or nitrous oxide (N₂O) may for this purpose be stored in the fluid storage 58. The control system 54 may be controlling a valve 56 for providing the oxidizing fluid in the reaction chamber 6 from the fluid storage and controlling heating of the reaction chamber. After conversion of the silicon or silicon nitride layers into silicon oxide the silicon oxide may transmit the UV and no in situ clean may be required. The periodical in situ conversion with oxidizing gas may also be used as an alternative for purging the radiation transmitting or reflecting surfaces which may simplify the design of the apparatus.

FIGS. 7a-7b depict an illumination system transmitting radiation according to yet a further embodiment. In FIG. 7a , a top view on an injector system 59 configured in a reaction chamber 6 is shown. In FIG. 7b , an enlarged side view on the injector system 59 of FIG. 7a is shown. The injector system 59 is provided with a gas inlet 61 and a gas outlet 63 and an illumination system 41. The illumination system 41 is provided with a radiation transmitting surface 53 to direct the ultraviolet radiation towards the gas in the injector system 59.

A processing gas may be provided through the injector system 59. The energy of the UV radiation from the illumination system 41 may activate the processing gas in the injector system so that it may react with the substrate in the reaction chamber 6 if it leaves the injector system through the gas outlet 63. The reactivity of the processing gas may be increased in this way to improve the reactivity on the substrate in the reaction chamber 6.

FIGS. 8a to 8c depict apparatus comprising an illumination system according to further embodiments. The reaction chamber 6, 7, may be limited by a process tube 65 forming a barrier for the process gas in the reaction chamber. The process tube may be (partially) functioning as a radiation transmitting surface. The illumination system may be provided outside the reaction chamber and may be constructed and arranged to irradiate the ultraviolet radiation through the radiation transmitting surface of the process tube 65 into the reaction chamber.

The illumination system 41 may be constructed and arranged to create the radiation between the process tube 65 and the outer tube 67 from a plasma. The illumination system 41 may be constructed and arranged to create the plasma by the system comprising a plasma gas supply system to provide the gases for the plasma between the process tube 65 and the outer tube 67. Noble gases such as argon, neon, krypton, and xenon may be provided between the process tube 65 and the outer tube 67 for this purpose. Also sodium or mercury may be provided between the process tube 65 and the outer tube 67 for this purpose.

FIG. 8a depicts that the illumination system 41 may comprises an anode 69 and a cathode 71 constructed and arranged to create a plasma in between the process tube 65 and the outer tube 67. The plasma may create ultraviolet radiation within a range from 100 to 500 nanometers. The ultraviolet radiation may illuminate a top surface of at least one of the substrates positioned within the process tube 65 according to a further embodiment.

FIG. 8b discloses which different plasma's may be created between the anode 69 and the cathode 71. Near the anode there is the anode plasma 73 and near the cathode 71 the cathode plasma 77. The positive column plasma 75 may be used for illumination of the substrates.

FIG. 8c depicts that the illumination system 41 according to a further embodiment may have induction device, for example, induction coils 79 which may be constructed and arranged to create a plasma in between the process tube 65 and the outer tube 67. The plasma may create ultraviolet radiation within a range from 100 to 500 nanometers. The illumination system may be constructed and arranged to radiate ultraviolet radiation with a range from 100 to 500, preferably 150 to 400, and even more preferably 170 to 300 nanometers. The ultraviolet radiation may illuminate a top surface of at least one of the substrates positioned within the process tube 65. The induction coils may also be used for heating the reaction chamber.

The ultraviolet radiation may be used to deposit, densify, atomic layer (ALD), chemical vapor deposition (CVD) or other layers. When layers are deposited in the reaction chamber the efficiency of the ultraviolet radiation system may be reduced drastically by absorption when a thickness of deposited material is adding up on top of the radiation transmitting surface on the inside of the process tube 65.

An in situ clean with etch gases may be required to clean the radiation transmitting surface. The apparatus may therefor comprise an etching system. The etching system may comprises a fluid storage 58, a control system 54 and a valve 56 as described in conjunction with FIG. 6 to provide an etching fluid, i.e., etchant in the reaction chamber 6 so as to etch a layer deposited on the process tube 65 away to improve the transmissivity of the process tube.

The radiation transmitting surface may also be made transmissive for the illumination radiation by converting a silicon or silicon nitride layers on the processing tube into silicon oxide by a thermal treatment in an oxidizing environment. The oxidizing environment may comprise, for example, oxygen (O₂), ozone (O₃), peroxide (H₂O2), water (H₂O), or Nitrous oxide (N₂O). The SiO₂ may transmit the UV and no in situ clean may be required.

The apparatus may therefore comprise a conversion system. The conversion system may comprise the fluid storage 58, the control system 54 and the valve 56. The control system 54 may be controlling a valve 56 for providing the oxidizing fluid in the reaction chamber 6 from the fluid storage and controlling heating of the reaction chamber 6. After conversion of the silicon or silicon nitride layers on the processing tube 65 into silicon oxide the silicon oxide may transmit the UV and no in situ clean may be required.

FIG. 9 depicts an illumination system according to a further embodiment. The illumination system 41 comprises individually controllable radiation sources, for example, light emitting diodes, to control the power output for illuminating the substrates 13 from the side individually along a stack of substrates in a vertical direction. The illumination system 41 for emitting radiation beams in the direction of the substrates 13 may be positioned on a side of the rack 12. The illumination system 41 may irradiate radiation beams from the side downward towards the top surface of the substrate 13. As shown here the illumination system only illuminates the top part of the rack 12 however in reality the illumination system 41 may be extended over the full length of the rack 12.

The angle of the radiation beams may be between 60 to 90° preferably between 80 to 89.5° and even more preferably between 85 and 89° with respect to a line perpendicular to the top surface of the substrate 13. The radiation beam of the illumination system 41 may be slightly parallel. The direction of the radiation beam of the illumination system may therefore be defined as the average direction of the radiation emitted by the illumination system 41.

The apparatus may comprise reflectors (not shown) on the other side of the substrate rack with respect to the illumination system 41 to reflect radiation reflected of the substrates 13 back to the substrate surface. The reflectors may be retroreflectors to reflect the radiation beam back in the same direction as from which the radiation beam came. The reflector may comprises a material selected from the group of material comprising glass, steel, aluminum or polytetrafluoroethylene (PTFE) to direct the radiation to the substrates.

The reflector may be provided with a polarizer to change the polarization of the reflected light by 90 degrees to improve the absorption of the reflected light. The polarizer may be a thin plate with a thickness of ⅛th of the wavelength positioned in front of the reflector.

The illumination system may have a first and second group of individually controllable radiation sources 91, 93. The first group of individually controllable radiation sources 91 may be directed to a surface of the substrate 13 further away from the edge and have an increased power output with respect to the second group of individually controllable radiation sources 93 directed to top surface near the edge of the substrate 13. The uniformity of the radiation intensity over the substrate surface may be increased in this way. If the radiation intensity is uniform over the substrate surface the reactivity increase by the illumination system 41 over the substrate surface becomes the same which is advantageously for process control.

As depicted the illumination system 41 may be directly illuminating the substrate 13 however the reaction chamber may also be limited by a process tube (shown in FIG. 8 as 65) in between the illumination system and the substrates 13. The process tube may be forming a barrier for processing gasses and at least partially functioning as the radiation transmitting surface. The illumination system 41 may be provided outside the reaction chamber and may be constructed and arranged to irradiate the ultraviolet radiation through the radiation transmitting surface into the reaction chamber. The process tube may be protecting the illumination system 41 from the alleviated temperature and deposition products provided in the reaction chamber.

FIG. 10 depicts an apparatus for processing a substrate comprising an illumination system according to a further embodiment. If the illumination system is provided from one side only a portion of the substrate 13 may be directly illuminated. By providing the apparatus with a rotation device to rotate the substrate the substrate in a direction as depicted by the arrow 95 it may be assured that the substrate 13 is uniformly illuminated.

The substrate rack 12 may be provided at the bottom with an insulating plug, which provides a seal with respect to the reaction chamber 6, 7 when the rack 12 is moved upward in the reaction chamber 6, 7 (see FIGS. 1 and 2). To increase the uniformity of the illumination by the illumination system 41 the insulating plug may be provided with a (rack) rotation device for rotating the rack 12 with substrates 13 around a vertical axis. Rack rotation devices may be known from U.S. Pat. No. 9,018,567 B2 incorporated herein by reference. The uniformity of the radiation intensity over the substrate surface may be increased in this way. If the radiation intensity is uniform over the substrate surface the reactivity increase by the illumination system 41 over the substrate surface becomes the same which is advantageously for process control.

FIG. 11 depicts a problem that may arise in the apparatus using an illumination system 41 to illuminate the substrates 13 and a (rack) rotation device for rotating the rack 12 with substrates 13 around a vertical axis. The radiation of the illumination system 41 may illuminate and or heat-up a part 12 a of the substrate rack excessively. The radiation may scatter from the substrate rack 12 through the ambient of the reaction chamber 6 illuminating parts of the apparatus that are not intended to be illuminated.

FIG. 12 depicts an illumination system according to a further embodiment solving the problem of excessive illuminating and or heating-up a part 12 a of the substrate rack in FIG. 11. The substrate rack 12 may be rotated to achieve a more uniform illumination distribution and circumvent excessive heating.

Further, the information of the shape of the substrate rack 12 and the rotation position of the rack 12 that is available from the control system may be used to switch off or limit the power of the part of the illumination system 41 that will be hitting the aforementioned part 12 a of the rack 12. A reduced amount of radiation may therefore be received by the part 12 a of the substrate rack 12 and less radiation may scatter from the substrate rack 12 through the ambient of the support member illuminating and heating up parts of the apparatus, that are not intended to be illuminated or heated up.

The apparatus may comprise a power controller 97 to control the power of the illumination system 41 and the power controller may be programmed to adjust a radiation output of the illumination system 41 along the width of the substrate rack to avoid excess heating of the substrate rack.

The particular implementations shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the aspects and implementations in any way. Indeed, for the sake of brevity, conventional manufacturing, connection, preparation, and other functional aspects of the system may not be described in detail. Furthermore, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and/or physical couplings between the various elements. Many alternative or additional functional relationship or physical connections may be present in the practical system, and/or may be absent in some embodiments.

It is to be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various acts illustrated may be performed in the sequence illustrated, in other sequences, or omitted in some cases.

The subject matter of the present disclosure includes all novel and nonobvious combinations and sub combinations of the various processes, systems, and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof. 

What is claimed is:
 1. A substrate processing apparatus comprising: a reaction chamber; a substrate rack for holding a plurality of substrates in the reaction chamber in a spaced apart relationship configured to rotate the substrate rack about an axis; and an illumination system constructed and arranged to irradiate ultraviolet radiation comprising a wavelength within a range from 100 to 500 nanometers onto a top surface of at least one of the substrates in the substrate rack from a side of the substrate rack; wherein a power controller is configured to at least one of switch off and limit power to a part of the illumination system to limit an amount of radiation hitting the substrate rack as it rotates around the axis.
 2. The apparatus of claim 1, wherein the power controller is configured to limit the electromagnetic radiation hitting the substrate rack such that a reduced amount of electromagnetic radiation is received by the substrate rack as compared to the electromagnetic radiation received by the at least one of the substrates.
 3. The apparatus of claim 1, wherein the power controller is configured to utilize information pertaining to a shape of the substrate rack and a rotational position of the substrate rack in order to limit the amount of radiation hitting the substrate rack as it rotates around the axis.
 4. The apparatus according to claim 1, wherein the apparatus comprises a heater for heating the substrates in the reaction chamber.
 5. The apparatus according to claim 1, wherein the apparatus is arranged to rotate the substrate rack around a vertical axis and the illumination system is arranged horizontally displaced from said vertical axis.
 6. The apparatus according to claim 1, wherein the illumination system is constructed and arranged to limit the radiation beam emitted from a side of the substrate rack downwards to a top surface of the substrate held in the substrate rack, such that an average direction of the radiation beam is limited to an angle between 60 to 90° with respect to a line perpendicular to the surface of the substrate.
 7. The apparatus according to claim 1, wherein the illumination system is constructed and arranged to limit the radiation beam emitted from a side of the substrate rack downwards to a top surface of the substrate held in the substrate rack, such that an average direction of the radiation beam is limited to an angle between 80 to 89.5° with respect to a line perpendicular to the surface of the substrate.
 8. The apparatus according to claim 7, wherein the illumination system is provided with a radiation transmitting or reflecting surface to direct the ultraviolet radiation to the substrates.
 9. The apparatus according to claim 8, wherein the apparatus is provided with a purge system for purging a radiation transmitting or reflecting surface in the reaction chamber.
 10. The apparatus according to claim 8, wherein the illumination system comprising the radiation transmitting or reflecting surface is provided partially within the reaction chamber.
 11. The apparatus according to claim 1, wherein at least one injector is provided within the reaction chamber for providing a fluid into the reaction chamber.
 12. The apparatus according to claim 1, further comprising a fluid storage comprising an oxidizing fluid for providing oxidizing fluid in the reaction chamber.
 13. The apparatus according to claim 1, further comprising a fluid storage comprising an etchant fluid for providing etchant fluid in the reaction chamber. 